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New Member

DHCP and Auxilary VLANs

I have a 6500 switch configured for Auxilary VLANs when i plug in my 7960 it gets the correct Voice Vlan ID from the switch but gets its DHCP address from the Data VLAN. I have dhcp running on the callmanager which is on the data vlan. I have 2 dhcp scopes configured on for for the data vlan and for the voice vlan. I am routing between the vlans and have ip-helper configured.

If i deactivate the data scope it works but the phones revert back when I reactivate it and reboot them. Its like even though the phone puts itself in the Auxilary Vlan it broadcasts out a dhcp request on both vlans and the data scope replies first.

Any help would be much appriecated

Cisco Employee

Re: DHCP and Auxilary VLANs

What software version are you running on the 6500? Look at the following bug

6.3(8) which has a fix is expected in next couple of days. As a workaround try lowering the cdp interval to 20 seconds.

Also, if you have configured the DHCP server switch port for data VLAN and Aux VLAN, remove the aux vlan from it. I have seen instances where Aux VLAN configuration on DHCP server port caused similar issues

New Member

Re: DHCP and Auxilary VLANs

Thanks a lot that fixed my problem

Cisco Employee

Re: DHCP and Auxilary VLANs

Great..Did changing the CDP interval fix the problem or was it the VLAN setting on the DHCP server port?

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